Cotton harvesters typically include a row unit structure with picker drums rotatable about upright axes adjacent a row-receiving area of the unit. The drum includes a plurality of upright picker bars having spindles which rotate in contact with cotton plants to remove the cotton. The spindles are aligned vertically in columns, and corresponding spindles on the bars define generally horizontal spindle planes, with a typical drum having eighteen to twenty spindle planes.
Doffers rotate between the spindle planes in contact with the spindles to doff cotton wound on the spindles and direct the cotton towards air door structure for removal from the unit towards a basket or processor. All the spindles on a spindle bar enter the doffing zone at the same time and cause a power requirement spike at the time of entry. In addition, all the cotton is doffed at the same time from the spindles of a bar, and the air system has to be able to handle the peak flow of cotton from all the spindles of a bar. An excess amount of cotton can get pinched between the aligned spindles and the doffer and cause plugging. Similarly, the cotton can also plug between the spindles and the moistener column.
A conventional picker bar includes a single row of spindles spaced uniformly in the vertical direction. Each spindle includes a gear end engaged by a mating bevel gear located on an upright spindle drive shaft supported for rotation within a hollow portion of the bar. The spacing between the spindle planes and thus the density of the spindles on the picker bar is limited by the spindle support and spindle drive arrangement. Currently available drive shaft bevel gear and the spindle nut mounting arrangements prevent closer spacing of spindles. Therefore, increasing the spindle density for increased drum productivity while maintaining the reliability of the spindle, spindle bar and spindle drive has been a continuing source of difficulty. In copending and commonly assigned U.S. application Ser. No. 11/058,150 entitled HIGH DENSITY COTTON PICKER BAR AND SPINDLE ASSEMBLY THEREFOR, filed Feb. 15, 2005, now U.S. Pat. No. 7,650,735, a picker bar is shown and described wherein spindles are nonaligned in the vertical direction to define two or more offset sets of spindles on the bar and facilitate closer vertical spacing of the spindles. Such a spindle bar with increased spindle density has been shown to improve picking efficiency but requires a complex and relatively expensive non-conventional spindle drive.